Numerical simulation of roof stratum effect on coal mass burst

The effects of roof stratum's physical properties, geometry parameters and movement states on rock burst danger were analyzed by numerical simulation with UDEC4.0 software. The results show that all the roof hanging distance, thickness, and intensity have an effect on coal mass burst. From half of the periodic weighting distance, the risk of coal mass burst increases obviously. The energy released has a logarithmic relation with the intensity of roof stratum, and an exponential relation with its thickness. The harder and thicker roof can generate greater dynamic stress on coal mass, easily increasing the risk of coal mass burst. In addition, the roof stratum in a movement state has a greater effect on rock burst than that in static state. Therefore, countermeasures such as weakening roof stratum intensity and shortening hanging distance can be taken to prevent coal mass from bursting. The roof blasting in NO.6303 working face of Ji-3 coal mine for outburst prevention show that this method is effective.